sudo apt-get install apt-mirror apt-mirror
At the time of release of 9.04, the repo for 8.10 took about 49GiB, and the repo for 9.04 took about 27GiB.
/etc/apt/mirror.list
Example:
deb http://archive.ubuntu.com/ubuntu intrepid main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu intrepid-updates main restricted universe multiverse #deb http://archive.ubuntu.com/ubuntu intrepid-backports main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu intrepid-security main restricted universe multiverse #deb http://archive.ubuntu.com/ubuntu intrepid-proposed main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu intrepid main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu intrepid-updates main restricted universe multiverse #deb-src http://archive.ubuntu.com/ubuntu intrepid-backports main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu intrepid-security main restricted universe multiverse #deb-src http://archive.ubuntu.com/ubuntu intrepid-proposed main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu jaunty main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu jaunty-updates main restricted universe multiverse #deb http://archive.ubuntu.com/ubuntu jaunty-backports main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu jaunty-security main restricted universe multiverse #deb http://archive.ubuntu.com/ubuntu jaunty-proposed main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu jaunty main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu jaunty-updates main restricted universe multiverse #deb-src http://archive.ubuntu.com/ubuntu jaunty-backports main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu jaunty-security main restricted universe multiverse #deb-src http://archive.ubuntu.com/ubuntu jaunty-proposed main restricted universe multiverse clean http://archive.ubuntu.com/ubuntu